$$\frac{ { x }^{ 4 } +1 }{ { x }^{ 2 } -x \sqrt{ 2 } +1 }$$
$\frac{x^{4}+1}{x^{2}-\sqrt{2}x+1}$
$\frac{2x^{5}-3\sqrt{2}x^{4}+4x^{3}-2x+\sqrt{2}}{\left(x^{2}-\sqrt{2}x+1\right)^{2}}$
